Chapter 10: Solids, Liquids, and Gases

Solid

Particles in solids are close together and are held in a fixed place. They have a definite shape and volume.

Liquid

Particles in liquids are close together and move freely past each other. They have a definite volume and adopt the shape of the container they are in.

Gas

Particles in gases are far apart and have little interaction. They adopt the shape and volume of the container they are in.

Phase Change

A transition from one state of matter to another.

Influencing Physical Properties

Stronger forces between particles result in higher melting and boiling points. More energy (heat) is needed to break stronger forces and allow a substance to change phases.

Ionic Substances

Lattices are rigid frameworks of atoms, molecules, or ions. Most ionic substances have high melting points.

Metallic Substances

Form lattices of tightly packed atoms. Electrons move easily between atoms. They conduct electricity and can be easily altered in shape (malleable) or stretched into wires (ductile).

Molecular Substances

Composed of discrete molecules. Forces within molecules are covalent bonds/molecules, while forces between molecules are intermolecular forces. They have lower melting and boiling points compared to ionic substances.

Intermolecular Forces

Forces between molecules. Three key groups are dipole-dipole interactions (DD), hydrogen bonds, and dispersion forces.

Dipole-Dipole Interactions

Attractions between polar covalent molecules. Molecules of a compound stick together because of the attraction of the positive and negative poles.

Hydrogen Bonding

The strongest of intermolecular forces. It occurs between molecules containing H-F, H-O, or H-N bonds.

London Dispersion

The weakest of the intermolecular forces. It occurs between non-polar molecules and atoms. Temporary dipoles form when atoms or molecules interact.

Ideal Gas

The volume of gas particles is much less than the volume of the container. The particles have no attraction for each other and bounce off of each other.

Pressure

The force that gases exert on their surroundings. It is measured in units such as millimeters of mercury (mm Hg) or torr.

The Gas Laws

Boyle's Law states that the pressure and volume of a gas are inversely related. Charles's Law states that the volume of a gas is directly proportional to its temperature. The Combined Gas Law is used when multiple variables are changing.

The Kelvin Scale

Absolute zero is -273.15 degrees Celsius or 0 K. Gas laws must always be in Kelvin.

Avogadro's Law

If temperature and pressure are constant, the volume of a gas is proportional to the number of moles of gas present.

The Ideal Gas Law

Relates the amount of gas to its pressure, volume, and temperature. It is represented by the equation PV = nRT.

Mixtures of Gases

Partial Pressure:Partial pressure is the pressure caused by one gas in a mixture. The total pressure is the sum of all partial pressures.

Diffusion

The spread of particles through random motion. Lighter particles diffuse more quickly.

Effusion

The process of a gas escaping from a container. It depends on the velocity of the gas particles. Lighter particles effuse faster.